On the rise of the ordinal number "first" in Medieval English

The word first was very rare in Old English, which mostly used forma, firmest and ærest in both spatial and temporal senses. All the three OE words became obsolescent in the 14th century while first, most likely supported by the fact that Old Norse had a similarly shaped cognate word, increased its occurrence and range of senses in early Middle English. By 1400 first had become the usual word denoting the front position and temporal antecedence both as an adjective and an adverb. Simultaneously it outcompeted the equivalent words in the function of the ordinal number.